1. Field of the Invention
One embodiment of the present invention relates to an input-output device. Another embodiment of the present invention relates to a method for driving an input-output device.
2. Description of the Related Art
In recent years, devices having a function of outputting data and a function of inputting data with incident light (such devices are also referred to as input-output devices) have been developed.
An example of an input-output device is an input-output device that includes a pixel portion including a plurality of light detection circuits (also referred to as optical sensors) arranged in the row and column directions and, as a light source, a backlight including light-emitting diodes of a plurality of colors (e.g., Patent Document 1). In the input-output device disclosed in Patent Document 1, in each frame period, the backlight is lit while colors of emitted light are switched to display a full-color image, and light reflected by an object subjected to reading is read as data. That is, the input-output device disclosed in Patent Document 1 functions as a touch panel. Note that a method in which a backlight is lit while colors of emitted light are switched in each frame period is called a field sequential method.